This invention relates to cartridge based data storage systems. More particularly, the invention relates to a media hub and a method of attaching media to a hub.
Cartridge based tape and disk data storage devices for storing digital electronic information have been in use in the computer industry for several decades. Removable disk cartridges typically comprise an outer casing or shell that houses a disk-shaped magnetic, magneto-optical or optical storage medium upon which information can be stored. The cartridge shell often comprises upper and lower halves that are formed of injection molded plastic and are joined together to house the disk. Magnetic disk media can be either rigid or flexible and are mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive engages the disk hub in order to rotate the disk within the cartridge at a given speed. The outer shell of the cartridge typically has a media access opening proximate one edge to provide the recording heads of the drive with access to the disk. A shutter or door mechanism is provided to cover the head access opening when the cartridge is not in use to prevent dust or other contaminants from entering the cartridge and settling on the recording surface of the disk. The shutter is commonly biased to a closed position with a spring bias. To open the shutter and gain access to the media, the drive employs a mechanism that overcomes the bias of the spring.
Such a cartridge is disclosed in U.S. Pat. No. 4,517,617 (Tsuji). The Tsuji patent is generally directed to a disk cartridge that contains a flexible magnetic disk having a center core (i.e., a hub) and an apparatus for reading and recording information on the flexible magnetic disk. The disk cartridge comprises a flexible disk attached to a hub. The disk and hub assembly are sandwiched between an upper cover and a lower cover. To constrain the movement of the flexible disk within the cover, the hub has a center hollow which mates with a projection from the upper cover of the cassette. The shutter moves laterally across the faces of the disk cartridge exposing or covering a disk access opening.
Disk drives for use with such removable disk cartridges typically employ either a linear actuator mechanism or a radial arm actuator mechanism for positioning the read/write head(s) of the disk drive on the recording surface(s) of the storage medium, or disk. Because the disk cartridges are designed to be removable from the drive, the linear or radial arm actuators must be able to move off, and away from, the storage medium to a retracted position in order to prevent damage to the head(s) when a cartridge is inserted and removed from the disk drive. Moreover, many removable cartridge disk drives employ a pair of opposing read/write heads for recording and reproducing information on both sides of a storage medium. Typically, the opposing heads are disposed on flexible suspension arms at the distal end of an actuator that allow the heads to fly closely over the respective surfaces of the rotating disk. The opposing heads must be spread apart as they approach the edge of the disk during a head loading operation in order to avoid collision with the edge of the disk. Similarly, when the heads are unloaded from the disk, they must again be spread apart to avoid collision with the edge of the disk and each other.
When a disk cassette of the type described above is inserted into the disk drive, the hub of the disk and the spindle of the drive must engage to allow the drive to spin the disk at a required rate. Typically, the hub and spindle engagement is accomplished by either translating the cartridge above the spindle until the spindle aligns with the cartridge, then translating the cartridge downwardly until the hub and spindle engage. Alternatively, the spindle is lowered before the disk cartridge is inserted into the drive. After the disk cassette is fully inserted, or during insertion, the spindle is raised to engage the hub.
In applications having very little space to accommodate a storage device, such as hand-held computers, digital cameras, and the like, the above-described disk and drive arrangements present a variety of drawbacks. For example, raising the disk cassette above the spindle requires additional overhead space to allow the cartridge to move above the spindle. Where the spindle is lowered, additional space is required to accommodate the spindle and motor as they move down into the drive chassis. In either case, a thicker disk drive results. To reduce the overall dimensions of the drive and disk cassette, drawbacks of the prior art disk cassettes and removable media drives must be overcome.
Media hubs are typically constructed from a solid cast piece of material or stamped from sheet material. Where the hub is constructed as a solid piece, the weight of the hub may cause the hub to separate from the media when the cartridge is dropped. The separation problem is particularly a problem where the media is attached to the hub by adhesive.